This is a new project to be carried out in collaboration with J. Schlom and other clinical labs. In the reported period we have initiated serological characterization of colon cancer patients from vaccine trials. We have selected 16 previously identified serological cancer antigens for further evaluation. One of such antigens, histone deacetylase 3 (HDAC3), appears to be restricted to colon cancer. Neither HDAC1 or HDAC2, two closely related proteins, manifest themselves as serological antigens. We collaborated with D. Kuprash from Moscow to map the B cell epitopes to HDAC3 in colon cancer patients to a non-conserved region of class I HDAC.